Nappa Scars

The North Craven Fault at Nappa Scars, Austwick in the Yorkshire Dales.
The unconformity of Nappa Scars at Norber reveals the geological timeline of the Dales. Beneath the footpath lies cleaved siltstone of the Upper Ordovician Norber Formation, and above the path lie the horizontal bands of Carboniferous Great Scar Limestone. Separating the two is a layer of pebbly conglomerate called the unconformity which represents a gap of about a million years. During this period, tropical seas covered and eroded the top layer of the siltstone, and limestone formed around the broken pieces. The resulting conglomerate is a rubbly mixture of the old siltstone rocks and new limestone.